Email Server and DNS

So I figured a little break from the NSA was in order. I am looking for some info on current practice for an email server and SMTP delivery. It has been a while since I have had to setup an email server and I have been tasked with setting up a small one for a friend. My question centers around the server sending outgoing email and the current practices requirements for other servers to accept email Things like rDNS, SPF records, etc... I am pretty much set on the issue of incoming spam and virus. Probably overkill but it is checked at the Sophos UTM firewall and at the email server itself. Thanks, Robert